Microsoft To Make Office 365 Uptime Data Public

Microsoft will now publicly disclose the availability statistics for its cloud-based Office 365 service, the company announced on Thursday.

Previously, only current Office 365 subscribers were able to access those numbers. Following Thursday's announcement, Microsoft said those numbers will be published quarterly and be available for everyone to view via the Office 365 Trust Center.

Microsoft measures Office 365's availability using an "uptime number," which the company calculates as "the number of minutes that the Office 365 service is available in a calendar month as a percentage of the total number of minutes in that month." In the last four quarters ending on June 2013, Office 365's worldwide uptime numbers have been 99.98 percent, 99.97 percent, 99.94 percent and 99.97 percent, sequentially.

"The uptime number includes Exchange, SharePoint, Lync and Office Web Apps, weighted on the number of people using each of these services. Customers use these services together, so all of these are taken into account while calculating uptime," Microsoft said.

There are a few caveats with how Microsoft determines Office 365's uptime number. First, the uptime number does not factor in consumer subscribers of Office 365 -- it only includes Office 365 subscriptions for government, education and business users. It also does not take into account Office 365 ProPlus because that suite is locally installed on end-user devices.

Additionally, according to a Microsoft spokesperson, outages in Microsoft's SkyDrive Pro cloud storage service are not included in the Office 365 downtime calculations. While SkyDrive Pro is available as a standalone service, it is also bundled into several Office 365 business plans.

Microsoft's calculations of Office 365 availability do not count planned downtimes against the uptime number, just unplanned downtimes. The spokesperson explained Microsoft's definition of unplanned downtimes in an e-mail Thursday:

"Unplanned downtime is the result of events typically outside Microsoft's direct control. Unplanned events occur when one or more of the services included in the Office 365 suite are unavailable or unresponsive. We have no excluded length of time or % of user impacted. All unscheduled downtime, from the minute it starts until it is resolved, is counted against our SLAs."

Microsoft's Office 365 service-level agreement promises users 99.9 percent uptime, with Microsoft being required to compensate subscribers if they're short of the mark.

Unlike some other major cloud-application providers like Amazon Web Services and Google, Microsoft does not offer a public dashboard-type portal where anyone can view the state of Office 365 availability in real time -- a fact that has garnered criticism from some industry watchers. Microsoft in its announcement touted the Office 365 Service Health Dashboard as a tool for checking service status, but it is available only to current Office 365 subscribers and shows the status of only the services relevant to their account. (Microsoft does provide a public dashboard for checking the health of its Windows Azure cloud platform, as well as a dashboard for its consumer cloud products, such as Outlook and the no-cost version of SkyDrive.)

Microsoft also noted that it typically shares a "post-incident review" with impacted organizations in the wake of major service outages. The company plans to launch a mobile app aimed at delivering information on Office 365 service availability to administrators by year's end.